The present embodiments relate to medical imaging and, in particular, to curved reformation.
The vascular system may be imaged non-invasively using computed tomography (CT) and/or magnetic resonance imaging (MRI). Both CT and MRI provide high-resolution volumetric information for visualizing anatomical objects (e.g., heart chambers and vessels). CT may be used in conjunction with a “live” modality, such as fluoroscopy. For these types of imaging, projection images during the procedure are common. The CT and MRI data often contains too much information, so selection of part the information for display during the “live” procedure is valuable.
One of the established methods to display tubular information is to generate longitudinal cross sections intersecting the lumen (e.g., center line), wall, and surrounding tissue in a plane. If the vessel is considered to be made of many small segments, then this longitudinal cross-sectioning plane continuously orients itself to align with the segments. The resulting sub-set of the volume defined by the planes is rendered. This technique is commonly referred as curved planar reformation (CPR).
CPR may be extended to include multiple planes for different vessels, and the resultant image is rendered an algebraic combination of the voxel intensities on these multiple planes (e.g., maximum intensity or minimum intensity selected along a path through the multiple planes). This approach is known as curved multi-planar reformatting (CMPR). However, in CMPR, parts of the vessels might be superimposed by other vessels depending on the respectively selected intersecting planes. FIG. 1 shows a significant artifact (see the arrow) when there is superimposition of two vessels and the intervening space has some source of “noise,” such as a heart chamber filled with contrast or other foreign bodies (e.g., a stent). In this particular instance two vessels are superimposed. The vessel at the back has low contrast due to poor blood flow, such as caused by a blockage. The space in between these two vessels has the heart chamber, which is filled with contrast medium. The arrow shows the sharp change in contrast (e.g., a parallelogram shaped region) of intersection that does not match intensity of either of the vessels. Other artifacts may be result in CMPR.